Apropos of the recent Washington Post story on how Fairfax County planners are looking to reduce the density of redeveloped properties in Tysons Corner, Tyler Cowen writes:

It seems the eight “mini-cities” are on the way out.  Why?  The area’s Revolutionary War era roads can’t handle too much additional population density…

That is, in a nutshell, why Fairfax County cannot and will not become like central Arlington in the Ballston and Clarendon areas.  Recall that some time ago Tysons Corner was ranked as #4 in office space in the entire U.S., if it were to be counted as a city.  Many Fairfax County residents look upon Arlington as a quaint experiment, a kind of well-laid out duck pond in somebody’s backyard, but not a model for the broader suburban area.  The walkable part of Arlington is quite small compared to Tysons Corner (by the way I used to live at Tysons and also have spent time walking it) and density in central Arlington doesn’t threaten to crush much of anything…

Rent-seeker he may be, but he’s right to suggest that a much denser Tysons — no matter how well done — will overwhelm the local support roads of Vienna and McLean.  The bottom line is that path dependence is a very strong force in all these comparisons.

I have to say, this is a little bizarre. Let’s begin with the obvious — Tyler seems to approve of the fact that a local planning board will dictate the size of buildings which can be built. What is the justification for this, from his perspective? Presumably, reducing the opportunity to build in such an economically important area will have significant economic costs, which might well be far greater than the cost of added congestion. Why does Tyler think that the best way to address congestion is through onerous zoning restrictions, rather than, say, tolling or a congestion charge? There is no attempt here to examine the relative costs and benefits of various options; he just seems to yell “traffic!” and throw up his hands. That’s not a very economic approach.

There are other odd statements here. Tysons’ Revolutionary War era roads inhibit dense building, but Arlington’s and Alexandria’s do not? Tyler is wrong; in terms of land area and employment, Arlington’s walkable areas are quite comparable to Tysons. And what he doesn’t think to ask is why significant density in Arlington doesn’t threaten to crush much of anything. He seems to assume that it’s either because there aren’t that many people there (wrong), because the area was built to handle vertical density (wrong), or…something else.

There are several important factors. One is that Arlington has a greater residential population, much of which is built around Metro stations. At present, most Tysons workers live several miles or more away from their jobs and drive to get to them. Perhaps this choice reflects a preference for driving to work, but it’s difficult to know because residential options (and related amenities) are so limited within Tysons. If lots of housing opportunities are created within walking distance of Tysons jobs, workers will respond to the reduction in commuting costs made possible by such development and will relocate there. Congestion may actually speed this transition, ensuring that residential amenities grow more rapidly within Tysons and reinforcing the transition.

At any rate, a larger residential population within Tysons will mean that a larger share of Tysons workers will walk to work. The presence of Metro will mean that a larger share of commuters will take Metro to work. And here is one of the most important points of all. At present, most trips within the Tysons area require a person to get in his car and drive. Daytime errands, trips out to lunch, or meetings at buildings across the way mean, by and large, a car trip, because the pedestrian and transit infrastructure is so bad within the area, and because density is reduced as a result.

The big idea of the plan is to fix this. If you work in Clarendon you can walk to get lunch, walk to the nearby copy shop, and Metro to other offices in Ballston, and Rosslyn, and Washington. Not everyone gets around in this way. Many people continue to drive. But by creating the walking and transit options, a large share of the intra-area traffic is removed from roads, clearing the way for inbound and outbound traffic.

I suppose it is open to debate whether these traffic mitigating effects will offset increased demand for road space generated by the redevelopment, but Tyler seems uninterested in exploring the question. Certainly, the Arlington experiment offers hope for Tysons, even if Fairfax residents foolishly think of it as a duck pond while they cool their heels in traffic. And I’m not really sure what kind of future Tyler sees for Tysons in the absence of this kind of redevelopment.

At any rate, it does seem odd that once again, we have a libertarian-ish figure cheering on the planners’ decision to artificially reduce density.